A new, somewhat flexible metal conduit has been developed for containing electrical wires sealed and protected from the environment. However, the new conduit requires sealed end connectors to connect the conduit to electrical devices, junction boxes, etc.
The newly developed flexible conduit is formed of a plurality of interlocking sections of thin, arcuate metal members which present a continuous surface of alternating grooves and ridges on both the exterior and interior walls thereof, enabling the conduit to be flexible as well as air tight and liquid tight. Such flexible metal conduits with sealed end connectors would be particularly useful with lighting fixtures in suspended or plenum ceilings to prevent sprinkler systems shorting out the electrical wiring and to prevent smoke from escaping into the plenum ceiling in the event of a fire within the conduit or the raceway system. Electrical code requirements are particularly severe with regard to isolating the electrical system from the air in a suspended ceiling which normally serves as a return plenum in forced air heating systems.
Reference may be made for instance to U.S. Pat. Nos. 3,895,177 and 3,992,044, assigned to the same assignee as herein, wherein there is described a flexible conduit commonly referred to as Greenfield conduit having an air and liquid tight polyvinyl chloride (PVC) covering combined with sealed end connectors to form a conduit and connector assembly meeting electrical code requirements for use in plenum ceilings. In the event of a fire, however, it has been found that overheating of the PVC covering may cause toxic fumes to enter the forced air heating system from the plenum ceiling. While the aforementioned newly developed metal conduit would eliminate the possible toxic fume problem, the sealed end connectors used with the PVC covered Greenfield conduit cannot be used and are not adaptable for use with the new conduit.
It is thus desired to provide a smoke tight, liquid tight and dust tight, sealed end connector for the new conduit. Also, it is desired to provide the ready fabrication of a sealed conduit and connector assembly which can be made up either on the job-site or at a manufacturing facility.